This invention relates to sensorless operation of a switched reluctance electric machine.
A switched reluctance motor (SRM) is a viable candidate for various motor control applications due to its rugged and robust construction. A high-performance SRM drive is possible by appropriately scheduling the commutation angles using accurate rotor position and speed information. The position information for a SRM drive is usually, obtained from a position sensor, often a shaft-mounted encoder or resolver, which adds cost and complexity to the overall drive system.
Sensorless operation is a key feature required to make SRM drives industrially competitive. Sensorless operation is important for various applications due to the need for minimum package size, high reliability and low cost for electric motor driven actuators. Use of discrete position sensors adds cost and complexity to the overall drive system and generally reduces reliability especially in harsh environments. Reliable and accurate indirect position sensing for low-cost actuators using switched reluctance motors is a key step towards developing low-cost, high-performance actuators. Therefore, it is desired to have a reliable, robust and preferably low-cost indirect source of position information for high-performance SRM drives.
Disclosed herein is a method for sensorless control of a switched reluctance electric machine comprising: probing a selected diagnostic phase of a switched reluctance electric machine with a pulse injection process; measuring an actual operating characteristic of the switched reluctance electric machine; computing an inductance based on the actual operating characteristic and correlating the inductance with a position to formulate an estimated position; modeling the switched reluctance electric machine to formulate a modeled position; selecting at least one of the estimated position, the modeled position, or a combination thereof to formulate a selected position of the switched reluctance machine; controlling the switched reluctance machine based on the selected position and a desired command.
Also disclosed herein is a system for control of a switched reluctance electric machine comprising: a switched reluctance electric machine including a sensor generating and transmitting a sensor signal indicative of an operating characteristic; a controller operatively coupled to the switched reluctance motor and the sensor; and the controller executing the following method. The method comprises: probing a selected diagnostic phase of the switched reluctance electric machine with a pulse injection process; measuring an actual operating characteristic of the switched reluctance electric machine; computing an inductance based on the actual operating characteristic and correlating the inductance with a position to formulate an estimated position; modeling the switched reluctance electric machine to formulate a modeled position; selecting at least one of the estimated position, the modeled position, or a combination thereof to formulate a selected position of the switched reluctance machine; and controlling said switched reluctance machine based on said selected position and a desired command.
Further disclosed herein is a system for controlling a switched reluctance motor in a vehicle steering system comprising: a means for probing a selected diagnostic phase of the switched reluctance electric machine with a pulse injection process; a means for measuring an actual operating characteristic of the switched reluctance electric machine; a means for computing an inductance based on the actual operating characteristic and correlating the inductance with a position to formulate an estimated position; a means for modeling the switched reluctance electric machine to formulate a modeled position; a means for selecting at least one of the estimated position, the modeled position, or a combination thereof to formulate a selected position of the switched reluctance machine; and a means for controlling the switched reluctance machine based on the selected position and a desired command.
Also disclosed herein in another embodiment is a steering system with a switched reluctance electric motor comprising: a steerable wheel coupled to a switched reluctance motor; a controller operatively coupled to the switched reluctance motor; the controller generating command to direct said switched reluctance motor. The controller also executes a method for control comprising: probing a selected diagnostic phase of the switched reluctance electric machine with a pulse injection process; measuring an actual operating characteristic of the switched reluctance electric machine; computing an inductance based on the actual operating characteristic and correlating the inductance with a position to formulate an estimated position; modeling the switched reluctance electric machine to formulate a modeled position; selecting at least one of the estimated position, the modeled position, or a combination thereof to formulate a selected position of the switched reluctance machine; and controlling the switched reluctance machine based on the selected position and a desired command.
Also disclosed herein in yet another exemplary embodiment is a storage medium encoded with a machine-readable computer program code, the computer program code including instructions for causing a controller to implement the abovementioned method for control of a switched reluctance electric machine.
Further disclosed herein in yet another exemplary embodiment is a computer data signal, the data signal comprising code configured to cause a controller to implement the abovementioned method for control of a switched reluctance electric machine.